diff --git a/lib/dry/schema/config.rb b/lib/dry/schema/config.rb
index 0cefa569..2d2244a6 100644
--- a/lib/dry/schema/config.rb
+++ b/lib/dry/schema/config.rb
@@ -46,7 +46,7 @@ class Config
         setting :backend, default: :yaml
         setting :namespace
         setting :load_paths, default: ::Set[DEFAULT_MESSAGES_PATH], constructor: :dup.to_proc
-        setting :top_namespace, default: DEFAULT_MESSAGES_ROOT
+        setting :top_namespace, default: DEFAULT_MESSAGES_ROOT, constructor: :to_s.to_proc
         setting :default_locale
       end
 
diff --git a/spec/integration/messages/namespaced_spec.rb b/spec/integration/messages/namespaced_spec.rb
index cb586bba..1f097dec 100644
--- a/spec/integration/messages/namespaced_spec.rb
+++ b/spec/integration/messages/namespaced_spec.rb
@@ -89,5 +89,12 @@
 
       expect(result.errors(full: true)[:post_body]).to eql(["(dry_validation) Post body must be filled"])
     end
+
+    it "allows symbol for top namespace" do
+      schema = Dry::Schema.Params do
+        config.messages.top_namespace = :dry_validation
+      end
+      expect(schema.config.messages.top_namespace).to eql "dry_validation"
+    end
   end
 end